Open Source Tracking Solar Concentrator Tutorials Finished

Nice project and nice animations. Thanks for the post.

What software did you use to make the animations?

Thanks,

Bruce

Ta.

Modelled in Rhino3D, animated etc in Maya, compd in AfterFX.

Thank you,

Bruce

Nice animations and clever use of an old bicycle, how about one that shows how the worm gear tracking mechanism works. I understand how it tracks throughout the day, but how does it get reset for the next day?

Ah yes, that is still missing. It will be implemented, and I have a couple ideas on how to do so, but haven't had a chance yet.

Was thinking a bimetalic strip (aluminium, steel, and rivets) in a conical mirror hung on the main collector to always face east, which heats at sunrise and pulls a brake cable which detaches the spring worm gear from the sprocket. The collector is slightly heavier on that side and falls back to reset, which takes the cone out of the light, the strip restores and a spring reconnects the work to the sprocket.

Or something like that.

Thanks, question 2 is how do you get the working fluid (ethanol) back up to the reservoir? It won't just rise up due to the difference in temperature.

The reservoir behind the boiler?

Yeah that was tricky to figure out, but turned out to be quite simple.

The sun moves onto the boiler, which after a minute or two starts producing vapour, which forces some liquid eths out of the tin, which pours onto the wheel, which turns the worm, which turns the collector, to which the box is attached, which shifts the sun off the boiler, which shuts down the boil. The vapour in the tin collapses, which creates a vacuum, which due to the bike valves at each end of the system sucks liquid from the reservoir below the wheel through the boiler and into the tin, refilling both.

That was the easy part, trickier was how to refill while the sun's still on the boiler because the system is caching up if it was cloudy for a couple of hours or something. Although that solution turned out pretty simple as well, just took me ages to think of.

The flattened copper boiler tube contains about 10ml of eths, the tin about 400ml. In practice they run out about the same time, ie the 10ml has boiled away around the time the vapour it's produced has forced out all the liquid in the tin. This is about enough to cover half the 50 degree / 2.5 hour range of the box.

So no more vapour is being produced to replace the vapour which is now collapsing, which creates a vacuum... and the whole thing refills itself. However the sun is still on the boiler, so after a minute it starts boiling again...

Repeat until the device has caught up with the sun, when it goes back to one correction every 1.5 minutes or so.

I figured that you were somehow using the perceived vacuum but I didn't see the use of the Schrader valves as check valves. I'm not a mechanical engineer so far be it for me to comment on your design but I've been studying solar power systems since the mid-70's, so please accept my comments as inquisitiveness based on experience.

1. Have you checked that the boiling ethanol produces enough pressure to overcome the spring pressure on the Schrader valve?

2. Since you're relying on the vacuum you need to be sure that there are no air leaks anywhere in the system, otherwise after a few heat-cool cycles the pressures will equalize and the ethanol won't recycle.

3. Be aware that ethanol is a very powerful solvent and will attack certain plastics and rubbers, as well as degreasing your bearings.

4. Make sure your entire collector is nearly perfectly balanced to minimize the effects of friction on your drive mechanism so as to reduce the load on your drive motor.

Good luck in your efforts, and remember that in 1903 a pair of bicycle mechanics ignored conventional wisdom and brought us flight!

> enough pressure to overcome the spring pressure on the Schrader valve?

Using Woods valves, aka English valves. No spring. I'd like to see if removing the spring from a Schraeder makes it usable, as they're a lot more common in some parts of the world.

> you need to be sure that there are no air leaks anywhere in the system

Yep. A lot of the work was in coming up with simple procedures that would result in an airtight system, only field testing will see if improvements need to be made. One thing I was considering is to increase the size of the boiler, so that it still produces vapour when the tin is empty of liquid, thereby hopefully forcing out any air that has ended up there.

> ethanol is a very powerful solvent and will attack certain plastics and rubbers, as well as degreasing your bearings.

Indeed. Especially hot ethanol. I have slight concerns for the plastic beads in the Woods valves, but they're easily replaced if they do perish. The rest should be reasonably ok. Can grease the bearing with vaseline if necessary, which doesn't dissolve in ethanol.

> Make sure your entire collector is nearly perfectly balanced

Oh very much so yes. This is the main thing to watch out for in the build. Nicely balanced a single M10 nut in a wheel cup will turn device, unbalanced it won't turn at all. Tuning isn't hard tho.

Just about the best practical explanation of a green project that I've seen online . Many thanks . Going to start collecting ali sheets asap . Good luck . Tom (Scotland ) .

genius...